The final piece of the puzzle is the size comparison between the valve’s square stem and the actuator’s shaft. One of two scenarios is likely. The first is that the dimensions will match and the components will mate perfectly. In this case, no additional hardware is needed aside from the four bolts to attach the actuator to the valve.

The other common circumstance is that the actuator shaft is larger than the valve’s stem. Just like the multiple flange patterns, this design is done for flexibility. A simple reducing sleeve can be placed over the valve stem to change its square dimension to match the actuator’s shaft. Though very uncommon, if the actuator shaft is smaller than the valve’s stem, consider increasing the actuator size to a point where the two components can be directly connected. The exception to this would be if upsizing causes the flanges to no longer match. Then a mounting kit will be needed regardless.